From: Zhang Qiao <zhangqiao22@huawei.com>
To: Tejun Heo <tj@kernel.org>
Cc: <peterz@infradead.org>, <juri.lelli@redhat.com>,
<linux-kernel@vger.kernel.org>, <mingo@redhat.com>,
<vincent.guittot@linaro.org>
Subject: Re: [PATCH] kernel/sched: Fix sched_fork() access an invalid sched_task_group
Date: Wed, 1 Sep 2021 15:43:00 +0800 [thread overview]
Message-ID: <128d52ab-b4ee-65f8-e0a3-2796ef43a98b@huawei.com> (raw)
In-Reply-To: <YS60T2bfLpxb6SUY@slm.duckdns.org>
hello,tejun.
在 2021/9/1 6:59, Tejun Heo 写道:
> Hello,
>
> On Tue, Aug 31, 2021 at 03:58:42PM +0800, Zhang Qiao wrote:
>>> I think this would allow cgroup migrations to take place before
>>> sched_post_fork() is run, which likely will break stuff. The right
cgroup migrations? Do you mean child process set its cgroups at
cgroup_subsys->fork()?
>>> thing to do likely is taking sched_task_group (and whatever other
>>> fields) after cgroup_can_fork(), which fixates the cgroup memberships,
>>
>> But it still seems possible that it accessed an invalid sched_task_group?
>> because the child process does not update its sched_task_group util
>> cgroup_post_fork().
>
> Between cgroup_can_fork() and cgroup_post_fork(), the cgroup membership and
> thus sched_task_group can't change, so if the child sets it to the parent's
> inbetween, the sched_task_group can't go away.
so the child just need to update its sched_task_group after cgroup_can_fork(),
then call sched_fork(), is it right?
thanks.
--
Qiao Zhang.
>
> Thanks.
>
next prev parent reply other threads:[~2021-09-01 7:43 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-26 11:26 [PATCH] kernel/sched: Fix sched_fork() access an invalid sched_task_group Zhang Qiao
2021-08-30 11:49 ` Zhang Qiao
2021-08-30 14:39 ` Peter Zijlstra
2021-08-30 17:32 ` Tejun Heo
2021-08-31 7:58 ` Zhang Qiao
2021-08-31 22:59 ` Tejun Heo
2021-09-01 7:43 ` Zhang Qiao [this message]
2021-09-01 16:45 ` Tejun Heo
2021-09-02 7:42 ` Zhang Qiao
2021-09-07 17:01 ` Tejun Heo
2021-09-08 11:32 ` Zhang Qiao
2021-09-08 16:29 ` Tejun Heo
2021-09-09 9:45 ` Zhang Qiao
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